Untitled - Laboratoire d'Astrophysique de l'Observatoire de Grenoble

controls the level of the anomalous transport observed in simulations. We plan to address the role of reconnection
(non-relativistic and relativistic) in turbulent transport by means of numerical simulations in the Hall-MHD
framework, following recent advances in the fusion context on this topic. This is a fundamental work that will
have quite universal applications. Of course, this is a very difficult branch of numerical physics requiring more
manpower than that currently available in the group, considering international standards. Therefore, hiring a
young researcher with a large expertise in both theoretical and numerical MHD is of primary importance in the
mid-term, to keep up with international competition.
Astrocladistics is now on the trails and two kinds of directions will be followed in parallel. The first one
is the extension of its application to many more galaxies in the Universe. For instance, the integration of the
Active Galactic Nuclei properties is a necessary and challenging task. In addition, with people in Toulouse, we
are exploring higher redshift objects using big surveys in the making, like the Sloan Digital Sky Survey (SDSS).
After this work (2006) we will strongly connect ourselves to the Virtual Observatory project which will probably
be the ideal data base to feed astrocladistics analyses. The second direction of work is on the theoretical side,
particularly in collaboration with mathematicians in cladistics (statistics, classification, complexity), but also
of course with astrophysicists specialized in galaxy physics and chemistry (interactions, stellar components,
interstellar medium, gas and dust, etc...), as well as in cosmology (the very first objects of the Universe). A new
taxonomy for galaxy classification will be proposed during the next few years (2007). It must be noted that
cladistic analyses are heavily CPU demanding, and clusters and even grids of PCs are necessary to perform the
calculations. A thesis subject (astrophysics) and a post-doc profile (cladistics/mathematics) will be proposed
in 2006.
Although mainly devoted to theoretical works, the SHERPA group has also been involved in many instrumental
collaborations, and intends to strengthen and develop this part of its activity, in the near, mid and long
term projects. In the near future, it will actively initiate or collaborate to observing proposals with existing
instruments : XMM, INTEGRAL, HESS. XMM and INTEGRAL are particularly valuable to study the high
energy emission of compact objects, due to their excellent collection area, allowing fast temporal studies. The
group has initiated in particular a new method to search for rapid QPOs in INTEGRAL data, allowing to
extend their study at high energy (above 20 keV). Thanks to RXTE observations, these QPOs are well known
to exist in galactic compact objects (X-ray binaries and micro quasars) at lower energy, but their spectrum
is poorly known. A progress in this field could bring very strong constraints on the mechanism responsible
for these oscillations, which is still a matter on intense debate. The new analysis technique should be used in
the next years to study archival data and initiate new proposals. The combination of XMM and INTEGRAL
observations is also very valuable, and one of us (P.O. Petrucci) has already strong experience in this type of
proposals. The collaboration with HESS, which the group is officially associated with, will of course continue.
The rapid growth of detected blazars will provide numerous data of good quality, allowing detailed comparisons
with time dependant simulations which have been developed in the group and will be improved in the next
future by the inclusion of a better description of acceleration mechanisms (T. Boutelier’s thesis, starting in
october 2005). Of course, the active participation to HESS shifts will go further.
On a longer term, improvements of the existing instruments as well as the launching of new ones is expected.
The HESS 2 project will increase significantly the collection area of the instrument, allowing a better sensitivity
and the detection of new objects, particularly TeV blazars. A very important application is the indirect
measurement of Cosmic Infra Red Background (CIRB), which absorbs the TeV photons and increases the
spectral index of a distant source. Another exciting discovery is the possible measurement of TeV emission
from a micro-quasar, which would confirm the link between the physics of galactic black holes and extragalactic
ones. The launching of GLAST, planned in 2007, is likely to open a new era in gamma-ray astronomy. Its
unprecedented sensitivity will allow to study a very large number of galactic and extragalactic objects in tha
gamma ray range, bridging the current gap between INTEGRAL (below 1 MeV) and Atmospheric Cerenkov
Telescopes (above 100 GeV). G. Pelletier and G. Henri are officially associated to the project as scientists.
However, because of their teaching duties, the group will need to hire a new young researcher in order to
maintain the reactivity demanded by the scientific support of High Energy facilities (like HESS and GLAST).
Because of its scientific position, the SHERPA group is also involved in two important intrumental projects
that should be operative in the next decade. The first one is the SIMBOL-X hard X-ray mission, operating in
the ∼0.5-70 keV range and with two orders of magnitude improvement in angular resolution and sensitivity,
which is proposed by a consortium of European laboratories (PI: P. Ferrando from Saclay). This will allow to
elucidate outstanding questions in high energy astrophysics, related in particular to the physics of accretion
onto compact objects, to the acceleration of particles to the highest energies, and to the nature of the Cosmic X-
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